AH.*  •    ,C^ 


* 


Issued  April  15, 1913. 


U.  S.  DEPARTMENT   OF  AGK'i'lULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— Bulletin   I 

A.  D.  Mhl.VIN,  Chief  ok  Bureau. 


THE  ACTION  OF  ARSENICAL  DIPS  IN  PROTECTING 
CATTLE  FROM  INFESTATION  WITH  TICKS. 


BY 


H.  W.  GRAYBILL,  D.  V.  M., 

Assistant  Zoologist,  Zoological  Division. 


m 


WASHINGTON: 
GOi^-^NME^IT  PRINTING  OFFICE. 
.,**      A       1913. 


WMENT  P 


>/ 


Issued  April  15, 1913. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  167. 

A.  D.  MELVIN,  Chief  of  Bureau. 


THE  ACTION  OF  ARSENICAL  DIPS  IN  PROTECTING 
CATTLE  FROM  INFESTATION  WITH  TICKS. 


BY 


H.  W.  GRAYBILL,  D.  V.  M., 
Assistant  Zoologist,  Zoological  Division, 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1913. 


BUREAU  OF  ANIMAL  INDUSTRY, 


Chief:  A.  D.  Melvin. 

Assistant  Chief:  A.  M.  Farrington. 

Chief  Clerk:  Charles  C.  Carroll. 

Animal  Husbandry  Division:  George  M.  Rommel,  chief. 

Biochemic  Division:  M.  Dorset,  chief. 

Dairy  Division:  B.  H.  Rawl,  chief. 

Field  Inspection  Division:  R.  A.  Ramsay,  chief. 

Meat  Inspection  Division:  R.  P.  Steddom,  chief.  % 

Pathological  Division:  John  R.  Mohler,  chief. 

Quarantine  Division:  Richard  W.  Hickman,  chief. 

Zoological  Division:  B.  H.  Ransom,  chief. 

Experiment  Station:  E.  C.  Schroeder,  superintendent. 

Editor:  James  M.  Pickens. 

ZOOLOGICAL  DIVISION. 

Chief:  B.  H.  Ransom. 

Assistant  Zoologists:  Albert  Hassall,  Harry  W.  Graybill,  Maurice  C.  Hall, 
and  Howard  Crawley. 
Junior  Zoologist:  Winthrop  D.  Foster. 
2 


LETTER  OF  TRANSMITTAL. 


United  States  Department  of  Agriculture, 

Bureau  of  Animal  Industry, 
Washington,  D.  C,  January  23,  1913. 

Sir:  I  have  the  honor  to  transmit  for  publication  as  a  bulletin  of 
this  bureau  the  accompanying  manuscript  entitled  "The  Action  of 
Arsenical  Dips  in  Protecting  Cattle  from  Infestation  with  Ticks,"  by 
Dr.  H.  W.  Graybill,  of  the  Zoological  Division  of  this  bureau. 

The  work  herein  described  was  undertaken  mainly  for  the  purpose 
of  determining  to  what  extent  and  how  long  an  arsenical  dip  protects 
cattle  from  infestation  with  ticks  after  dipping.  Three  experiments 
were  conducted  with  cattle,  by  which  it  was  found  that  infestation 
was  prevented  for  two  days,  and  that  there  was  no  protection  when 
the  exposure  to  infestation  occurred  five  days  or  longer  after  dipping. 
Further  experiments  to  ascertain  if  the  protection  extends  beyond 
two  days  are  in  progress  and  will  be  reported  later. 

The  present  work  includes  a  series  of  experiments  made  with  cattle 

ticks  to  determine  the  manner  in  which  substances  used  in  dips  (oils 

and  arsenic)  act  upon  them.     It  is  shown  that  ticks  are  destroyed  by 

dips  either  by  suffocation  or  by  poisoning,  or  by  both. 

Respectfully, 

A.  D.  Melvix, 

Chief  of  B  ureau. 
Hon.  James  Wilson, 

Secretary  of  Agriculture. 

3 


CONTENTS 


Page. 

Summary 5 

Introduction 6 

Composition  of  arsenical  dips 8 

The  manner  in  which  dips  act  on  ticks 9 

The  action  of  oils  and  other  substances  on  ticks 9 

Smearing  the  spiracles 9 

Smearing  the  scutum  and  mouth  parts 12 

Dipping  the  ticks  in  oils 13 

The  effect  of  arsenic  on  ticks 15 

Cattle-dipping  experiments  to  ascertain  the  protective  action  of  arsenical  dips.  16 
Experiment  No.  1. — Cattle  exposed  to  infestation  at  various  intervals  from 

a  few  hours  to  four  weeks  after  dipping 16 

Observations  on  engorged  ticks  removed  from  the  animals 17 

Discussion  of  results 19 

Experiment  No.  2. — Cattle  exposed  to  infestation  2\  hours  and  two  days 

after  dipping 23 

Discussion  of  results 24 

Death  of  animals  from  arsenical  poisoning 25 

Staining  of  tissues  of  animals  treated  with  trypan  blue 26 

Experiment  No.  3. — Cattle  exposed  to  infestation  five  days  after  dipping.  26 

Discussion  of  results 27 

The  method  by  which  animals  are  protected  against  tick  infestation 27 

4 


THE  ACTION  OF  ARSENICAL  DIPS  IN  PROTECTING  CATTLE  FROM 
INFESTATION  WITH  TICKS, 


SUMMARY. 


In  this  bulletin  the  factors  entering  into  the  efficacy  of  dips  used  against  ticks 
are  discussed.  Dips  act  both  in  a  direct  destructive  way  and  in  a  protective 
manner  preventing  infestation.  The  protective  action  of  a  dip  may  be  in  the 
nature  of  a  destructive  or  of  a  repellent  action.  The  influence  of  dips  on  ovi- 
position  and  the  viability  of  the  eggs  is  a  factor  in  efficacy. 

The  ingredients  of  homemade  arsenical  dips  and  the  known  or  probable 
functions  of  each  ingredient  are  discussed. 

It  is  suggested  herein  that  any  protective  action  that  the  usual  arsenical  dips 
might  have  would  be  expected  to  be  due  to  a  toxic  rather  than  to  a  repellent 
action.  Watkins-Pitchford  has  shown  that  cattle  dipped  in  arsenic  are  poisonous 
to  ticks. 

Ticks  are  destroyed  by  dips  either  by  suffocation  or  by  poisoning,  or  by  both 
means.  Tests  were  conducted  showing  that  ticks  are  suffocated  by  the  closing 
of  the  respiratory  openings  (spiracles).  It  was  found  that  practically  all  en- 
gorged females  that  had  their  spiracles  closed  with  Canada  balsam  died.  In 
other  tests  of  the  same  sort,  in  which  oils  were  used,  Beaumont  oil  proved  much 
less  effective  than  Canada  balsam,  and  cottonseed  oil  was  practically  without 
effect. 

Smearing  the  scutum  and  mouth  parts  of  engorged  females  with  oils  and  vis- 
cous substances  had  no  influence  on  the  mortality,  or  oviposition.  or  on  the  per 
cent  of  eggs  hatching. 

In  tests  in  which  engorged  females  were  dipped  in  Beaumont  oil  and  in 
cottonseed  oil  the  former  proved  very  much  more  effective  than  the  latter,  and 
this  is  due  in  all  probability  to  a  toxic  action.  Beaumont  oil  had  a  marked 
influence  on  oviposition,  on  the  number  of  eggs  deposited,  and  on  the  viability  of 
the  eggs,  whereas  cottonseed  oil  had  no  effect. 

The  possible  avenues  for  the  entrance  of  arsenic  into  the  bodies  of  ticks  are 
enumerated,  and  the  porose  areas  are  pointed  out  as  possible  vulnerable  points 
in  the  armor  of  the  tick. 

Three  cattle-dipping  experiments  were  conducted  with  an  arsenical  dip  con- 
taining 8  pounds  of  arsenic  trioxid  to  500  gallons  of  water,  in  order  to  test  its 
protective  action  against  tick  infestation.  Seed  ticks  were  placed  on  the  cattle 
at  varying  periods  after  they  were  dipped.  In  the  first  experiment  the  ticks 
were  placed  on  the  cattle  at  periods  ranging  from  a  few  hours  to  four  weeks, 
in  the  second  from  a  few  hours  to  two  days,  and  in  the  third  at  five  days  after 
dipping.  It  was  found  that  the  dip  rendered  no  protection  when  the  exposure  to 
infestation  was  five  days  or  longer  after  dipping.  The  limit  of  protection 
ascertained  in  the  experiments  was  two  days.  No  tests  were  made  covering 
the  intervening  period  between  two  and  five  days. 

Arsenical  poisoning  which  occurred  among  the  animals  in  one  experiment 
was  apparently  caused  by  undissolved  arsenic  in  the  dip.  It  would  therefore 
seem  that  undissolved  arsenic  in  a  dip  is  highly  dangerous. 


6  ACTION   OF  ARSENICAL  DIPS  AGAINST  CATTLE   TICKS. 

It  is  shown  conclusively  that  the  protective  action  of  arsenic  is  dependent  on 
its  toxic  action,  and  not  on  a  repellent  action. 

As  a  result  of  incidental  observations  made  on  engorged  female  ticks  from 
animals  suffering  from  Texas  fever  it  was  found  that  the  mortality  of  such 
ticks  may  be  very  high,  as  much  as  95  per  cent.  The  cause  for  this  is  not 
known.  It  may  be  nutritional  in  character,  due  to  the  changed  or  impoverished 
condition  of  the  blood  absorbed,  or  it  may  be  due  to  the  parasitism  of  Piro- 
plasma  Ugeminum,  the  microorganism  which  is  the  direct  cause  of  Texas  fever. 

Observations  made  for  the  purpose  of  determining  whether  there  was  any 
relationship  between  the  degree  of  infestation  and  the  time  elapsing  between  The 
last  dipping  and  the  infestation,  and  also  on  the  mortality  of  engorged  females 
from  dipped  animals  infested  subsequently  to  dipping,  as  compared  with  that  of 
ticks  from  undipped  animals,  were  inconclusive.  Oviposition  and  viability  of 
the  eggs  of  these  ticks  appeared  to  be  unaffected. 

INTRODUCTION. 

The  efficacy  of  a  dip  used  against  such  a  pest  as  the  cattle  tick  may 
be  considered  under  two  heads,  namely,  its  direct  destructive  action, 
and  its  protective  action  in  preventing  reinfestation.  (Protective 
action  may  be  the  result  either  of  a  destructive  or  of  a  repellent  action, 
or  of  both.)  These  properties  are  no  doubt  combined  to  a  certain 
degree  in  all  dips  that  have  proved  effective  against  ticks.  The  rela- 
tive importance  that  they  assume,  from  a  practical  standpoint,  de- 
pends on  the  particular  purpose  for  which  dipping  is  done.  If  it  is 
desired  to  render  cattle  free  of  ticks,  and  they  are  not  to  be  subjected 
to  the  dangers  of  reinfestation,  the  protective  value  of  the  dip  is  of 
minor  importance.  On  the  other  hand,  if  the  purpose  is  to  eradicate 
the  ticks  from  a  given  area,  and  the  animals  are  turned  back  on  in- 
fested fields  subsequent  to  each  treatment,  the  protective  value  of  a 
dip  assumes  considerable  importance.  In  the  former  case  the  pro- 
tective properties  would  be  of  value  only  in  case  the  animals  should 
by  accident  be  subjected  to  infestation  subsequent  to  dipping,  whereas 
in  the  latter  case  they  would  play  an  important  part  in  bringing 
about  extermination.  It  is  conceivable,  though  we  have  no  such  dips 
at  present,  that  a  dip  might  stand  low  in  its  direct  destructive  action 
and  still  prove  highly  effective  in  eradication  work  because  of  its 
protective  (repellent)  properties. 

In  addition  to  the  destructive  and  protective  qualities  of  a  dip 
another  factor  must  be  considered,  and  that  is  its  influence  on  ovipo- 
sition and  on  the  viability  of  the  eggs  deposited.  It  has  been  pointed 
out  in  Bulletin  «L44  of  the  Bureau  of  Animal  Industry  that  arsenic 
diminishes  both  the  number  of  eggs  deposited  by  females  that  survive 
and  to  a  marked  degree  the  viability  of  the  eggs.  Certain  oils  also 
affect  the  number  of  eggs  deposited  and  the  viability  of  the  eggs. 
Various  oils  are  known  to  be  more  or  less  effective  against  ticks,  and 
they  all  no  doubt  possess  a  certain  amount  of  protective  value,  de- 
pendent on  their  odor,  their  disagreeable  nature,  or  the  destructive 


INTRODUCTION.  7 

action  they  exert  when  seed  ticks  come  in  contact  with  them.  Other 
things  being  equal,  the  less  volatile  the  oil  the  longer  the  protective 
action  lasts. 

The  arsenical  dips  which  have  shown  a  high  degree  of  efficacy 
against  ticks  were  commonly  supposed  to  have  little  or  no  protective 
value  until  Watkins-Pitchford  *  in  1910  showed  by  experiments  that 
animals  dipped  in  arsenic  are  poisonous  to  ticks.  The  same  author  2 
in  other  experiments  found  that  16.8  per  cent  of  the  adult  ticks  that 
became  attached  to  cattle  shortly  after  dipping  in  arsenic  (4  pounds 
of  arsenite  of  soda  (80  per  cent  arsenic),  3  pounds  of  soft  soap,  and  1 
gallon  of  paraffin  to  make  400  gallons  of  dip)  were  dead  at  the  end 
of  three  days,  and  that  in  the  case  of  horses  22.5  per  cent  of  the  ticks 
were  dead.  In  one  experiment  in  which  horses  had  been  frequently 
dipped  the  tick  mortality  was  36.8  per  cent  among  ticks  that  attached 
during  the  course  of  three  days. 

Arsenical  dips  containing  sodium  metarsenite  in  alkaline  solution 
and  an  admixture  of  pine  tar  could  not  be  expected  to  exert  any 
repellent  action  because  of  their  physical  nature  or  their  odor,  except 
in  so  far  as  the  tar  is  concerned,  the  action  of  which,  however,  must 
be  very  slight.  Any  protective  value  that  such  dips  have,  therefore, 
must  necessarily  depend  largely  on  the  toxicity  of  the  arsenic  present 
on  or  in  the  skin  of  dipped  animals.  YVatkins-Pitchford  2  found 
that  the  arsenical  dip  above  mentioned  retarded  infestation  with 
larvae  and  nymphs  of  the  brown  tick.  The  time  between  treatment 
and  infestation  is  not  stated,  but  it  was  presumably  only  a  few  hours. 
The  author  attributed  the  protective  action  to  the  paraffin  component 
of  the  dip.  It  was  found  that  dipping  did  not  hinder  infestation 
with  the  adult  of  the  brown  tick,  but  that  the  number  on  cattle  sub- 
jected to  infestation  rapidly  decreased  as  a  result  of  the  poisonous 
effect  of  the  arsenic  present  in  the  skin  of  the  animals. 

In  the  work  of  .tick  suppression  and  tick  eradication  in  this  and 
other  countries  arsenical  dips  have  proved  satisfactory  when  used 
at  regular  intervals.  The  strength  of  the  dip  and  the  interval  be- 
tween treatments  have  been  determined  with  a  view  of  obtaining  the 
best  results  with  as  little  injury  to  the  cattle  as  possible.  The  inter- 
val between  dippings  has  rested  largely  on  an  empirical  basis,  except 
in  the  case  of  treatment  directed  against  certain  species  of  ticks  of 
economic  importance  in  South  Africa  that  drop  from  their  host 
previous  to  each  molt,  in  which  case  the  period  has  been  based  in 
some  instances  on  the  minimum  time  the  tick  has  been  found  to  re- 
main attached  to  the  host.     Little  is  known  as  to  how  much  the  ar- 

1  Natal  Agricultural  Journal,  Pietermaritzburg,  vol.  15,  no.  3,  Sept.,  1910,  pp.  312-328. 

2  Agricultural  Journal.  Union  of  South  Africa,  Pretoria,  vol.  2,  no.  1,  July,  1911,  pp. 
33-79.     Rhodesia  Agricultural  Journal,  Salisbury,  vol.  10,  no.  3,  Feb.,  1912,  pp.  372-100. 

78867°—  Bull.  167—13 2 


8  ACTION    OF   ARSENICAL   DIPS   AGAINST   CATTLE   TICKS. 

senical  dip  plays  in  a  protective  way  in  bringing  about  the  results 
that  have  been  attained.  It  was  with  a  view  of  determining  to  what 
extent  and  for  how  long  arsenic  protects  against  infestation  that  the 
experiments  detailed  in  this  paper  were  taken  up. 

COMPOSITION  OF  ARSENICAL  DIPS. 

Arsenic  seems  to  have  almost  a  specific  action  on  ticks.  The 
arsenical  dips  in  use  against  ticks  as  a  rule  have  their  arsenic  present 
in  the  form  of  sodium  or  potassium  metarsenite,  the  former  of  which, 
however,  in  the  presence  of  bacterial  growth,  as  shown  by  Fuller,1 
gradually  becomes  oxidized  to  the  arsenate.  In  the  home-made 
dips  used  in  this  country  the  only  other  ingredients  are  an  excess 
of  sodium  carbonate  and  pine  tar.  In  formulas  that  were  for- 
merly tried  in  this  country,  and  some  now  in  use  in  other  countries, 
there  are  other  ingredients,  such  as  soap  and  emulsified  paraffin 
(kerosene). 

Watkins-Pitchford  2  has  found  that  paraffin  emulsified  with  soap 
in  the  dip  ameliorates  its  irritative  action  and  that  the  addition  <;f 
emulsified  paraffin  and  glycerin  subdues  this  action  still  more.  It 
is  not  likely  that  the  soap,  pine  tar,  or  paraffin  exert  any  important 
destructive  action  on  ticks,  especially  in  view  of  the  fact  that  they 
constitute  less  than  1  per  cent  of  the  dip.  Watkins-Pitchford  ::  found 
that  the  mortality  of  ticks  in  the  case  of  two  arsenical  dips  was 
raised  1.8  and  5.7  per  cent  by  the  addition  of  soap  and  paraffin.  His 
observations,  however,  were  based  on  too  small  a  number  of  ticks  to 
be  considered  conclusive.  All  three  of  the  ingredients  mentioned 
may  serve  a  certain  function  in  causing  the  arsenic  to  adhere  more 
tenaciously  to  the  skin  and  hair,  and  the  tar  and  paraffin  may 
exert  a  slight  amount  of  repellent  action  because  of  their  odor  and 
physical  properties.  They  also  serve  the  purpose  of  giving  the  dip  a 
distinctive  character.  The  soap  serves  a  function  in  the  emulsifica- 
tion  of  the  tar  or  kerosene,  depending  on  which  is  used,  and  probably 
exerts  a  certain  amount  of  cleansing  effect  on  the  skin. 

The  excess  of  sodium  carbonate  in  the  two  formulas  in  use  in  this 
country,  in  which  8  and  10  pounds  of  white  arsenic  are  used  to  24 
and  25  pounds,  respectively,  of  sodium  carbonate,  is  considerable. 
Whereas  only  1.45  parts  by  weight  of  sodium  carbonate  to  1  part  of 
arsenic  are  necessary  in  the  formation  of  sodium  metarsenite,  in  the 
above  formulas  2J  to  3  parts  are  used  to  each  part  of  arsenic.  How- 
ever, this  excess  of  sodium  carbonate  serves  a  number  of  important 
purposes.     It  facilitates  the  solution  of  the  arsenic,  aids  in  the  emul- 

1  Circular  182,  Bureau  Animal  Industry,  r.  S.  Department  of  Agriculture.  Washington, 
1911. 

•  Natal  Agricultural  Journal,  Pietermaritzburg,  vol.   12,  no.  4,  Apr.  .'50.  1900. 
Agricultural  Journal,  Union  of  South  Africa,  Pretoria,  vol.  2,  no.  1,  July,  1911,  pp.  33- 
79.     Rhodesia  Agricultural  Journal,  Salisbury,  vol.  10,  no.  3,  Feb.,  1912,  pp.  372-400. 


HOW   DIPS  ACT   ON   TICKS.  9 

sification  of  the  tar,  cleanses  the  skin  of  the  cattle,  and   possibly 
softens  the  cuticle  of  the  ticks  and  thus  facilitates  the  entrance  of 

arsenic. 

THE  MANNER  IN  WHICH  DIPS  ACT  ON  TICKS. 

When  ticks  are  destroyed  by  a  dip  they  are  killed  by  suffocation, 
by  being  poisoned,  or  by  a  combination  of  both  causes.  In  the  case 
of  the  use  of  such  substances  as  oils  it  is  probable  that  death  is  due 
both  to  suffocation  and  to  a  toxic  action. 

THE  ACTION  OF  OILS  AND  OTHER  SUBSTANCES  ON   TICKS. 
SMEARING    THE    SPIRACLES. 

That  ticks  may  be  suffocated  the  writer  has  shown  by  closing  the 
spiracles  of  engorged  females  of  the  cattle  tick  with  Canada  balsam. 
On  May  19,  1911,  10  engorged  females  that  had  already  begun  to 
oviposit  had  their  spiracles  closed  with  a  drop  of  balsam.  On  the 
following  day  the  ticks  were  normal  in  color  but  were  inactive,  their 
legs  being  stretched  out  straight.  On  the  third  day  all  the  ticks  had 
turned  dark  and  were  dead.  Xo  eggs  were  deposited.  In  the  con- 
trol lo£  of  10  ticks  -1  died.  Many  eggs  were  deposited,  40  per  cent 
of  which  hatched. 

In  order  to  determine  whether  the  xylol  in  the  balsam  may  not 
have  played  a  part  in  the  destruction  of  the  ticks  a  second  test  was 
made  on  May  2C>  in  which  the  spiracles  of  10  engorged  females  that 
had  begun  to  oviposit  were  touched  with  xylol.  One  tick  turned 
dark.  All  oviposited,  and  a  normal  number  of  eggs  were  deposited, 
about  30  per  cent  of  which  hatched. 

On  September  27,  1912.  another  lot  of  20  engorged  females  just 
collected  had  their  spiracles  touched  with  Canada  balsam.  On  Sep- 
tember 30  all  of  them  were  dead.  In  two  control  lots  of  20  engorged 
females  each,  collected  on  the  same  date,  all  the  ticks  remained  normal 
and  oviposited :  92  and  60  per  cent  of  the  eggs  hatched. 

On  September  29.  1912,  a  third  lot  of  20  engorged  females,  col- 
lected on  September  27.  1912.  had  their  spiracles  touched  with  Canada 
balsam.  Seventeen  of  the  ticks  were  killed,  the  remainder  deposited 
normal  eggs.  Eighty-seven  per  cent  of  the  eggs  hatched.  In  two 
control  lots  of  20  ticks  each,  collected  on  the  same  date  as  the  above 
lot,  all  oviposited  and  a  usual  number  of  normal  eggs  were  deposited ; 
92  and  80  per  cent  of  the  eggs  hatched. 

From  the  above  tests  it  may  be  definitely  concluded  that  a  com- 
plete closing  of  the  spiracles  of  engorged  females  will  lead  to  their 
destruction.  In  the  case  of  the  three  ticks  in  the  last  lot  that  sur- 
vived it  seems  safe  to  assume,  in  view  of  the  number  of  positive  tests, 
that  the  spiracles  were  not  completely  closed. 


10  ACTION   OF  ARSENICAL  DIPS  AGAINST  CATTLE   TICKS. 

Some  additional  tests  were  made  along  the  above  line  with  other 
oils.  On  May  13,  1911,  eight  engorged  females  that  had  already 
begun  to  oviposit  had  their  spiracles  smeared  with  Beaumont  crude 
petroleum.  All  but  one  continued  oviposition.  Three  of  the  ticks 
died.  Many  eggs  were  deposited,  25  per  cent  of  which  hatched.  In 
a  control  lot  of  seven  ticks  all  continued  oviposition.  Four  ticks 
died.  A  fair  number  of  eggs  were  deposited,  about  30  per  cent  of 
which  hatched. 

September  27,  1912,  20  engorged  females  collected  on  that  date 
had  their  spiracles  touched  with  crude  Beaumont  oil.  One  (5  per 
cent)  of  the  ticks  died.  It  had  apparently  been  injured  about  the 
head  when  removed  from  the  host.  Three  ticks  remained  plump. 
Nineteen  ticks  oviposited,  and  a  normal  number  of  eggs  were  pro- 
duced.   Seven  per  cent  of  the  eggs  hatched. 

September  27,  1912,  20  engorged  females  just  collected  had  their 
spiracles  touched  with  refined  cottonseed  oil.  None  died.  All  ovi- 
posited, and  a  normal  number  of  eggs  were  deposited.  Ninety-two 
per  cent  of  the  eggs  hatched. 

Two  control  lots  of  20  ticks  each,  collected  on  the  same  date  as  the 
above,  remained  normal.  All  the  ticks  oviposited,  and  a  normal 
number  of  eggs  were  produced;  92  and  60  per  cent  of  the  eggs 
hatched. 

On  September  27, 1912,  20  engorged  females  just  collected  had  their 
spiracles  touched  with  Beaumont  oil.  One  (5  per  cent)  failed  to 
oviposit.  Three  (15  per  cent)  died.  A  normal  number  of  eggs  were 
deposited.    Twenty  per  cent  of  the  eggs  hatched. 

On  September  28,  1912,  20  ticks  collected  on  September  27  had 
their  spiracles  touched  with  refined  cottonseed  oil.  None  of  the  ticks 
died.  All  the  ticks  oviposited,  and  a  normal  number  of  eggs  were 
deposited.    Ninety  per  cent  of  the  eggs  hatched. 

In  two  control  lots  of  20  ticks  each,  collected  on  the  same  date  as 
the  above,  none  died,  and  all  oviposited,  a  normal  number  of  eggs 
being  produced ;  80  and  92  per  cent  of  the  eggs  hatched. 

On  May  26,  1911,  10  engorged  females  that  had  begun  to  oviposit 
had  their  spiracles  touched  with  pine  tar.  All  oviposited,  and  a 
normal  number  of  eggs  were  deposited,  15  per  cent  of  which  hatched. 
In  the  control  lot  of  10  ticks,  all  but  one  oviposited,  and  five  died 
without  completing  oviposition.  Many  eggs  were  deposited,  10  per 
cent  of  which  hatched. 


HOW   DIPS  ACT  ON   TICKS. 


11 


Summary  of  tests  m  which  spiracles  of  engorged  females  were  smeared  with  oil. 


Date  of  experiment. 


May  13, 1911.. 

Do 

Sept.  27, 1912. 

Do 

Do 

Do 

Do 

Sept.  28,  1912. 
Sept.  27,  1912. 

Do 

May  26, 1911. . 

Do 


Mortal- 
ity. 


Per  cent. 
38 
57 
5 
0 
0 
0 
15 
0 
0 
0 


50 


Ticks 
oviposit- 
ing. 


Per  cent. 

88 
100 

95 
100 
100 
100 

95 
100 
100 
100 
100 

90 


Number  of 
eggs  deposited. 


Many.. 
Fair  . . . 
Normal 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
....do. 
Many . . 


Eggs 
hatched. 


Per  cent. 

25 

30 

7 

92 
92 
60 
20 
90 
80 
92 
15 
10 


Substance  used. 


Beaumont  oil. 
(Control.) 
Beaumont  oil. 
Cottonseed  oil. 
(Control.) 

Do. 
Beaumont  oil. 
Cottonseed  oil. 
(Control.) 

Do. 
Pine  tar. 
(Control.) 


It  is  noted  from  the  above  table  that  the  mortality  of  the  different 
lots  of  ticks  treated  with  Beaumont  oil  compared  with  that  of  the 
corresponding  controls  is  as  follows :  3'8  per  cent,  control  57  per  cent ; 
5  per  cent,  controls  0  per  cent ;  15  per  cent,  control's  0  per  cent.  This 
indicates  a  detrimental  effect  of  the  Beaumont  oil,  but  is  in  marked 
contrast  with  the  results  obtained  when  the  spiracles  were  closed  with 
Canada  balsam,  in  which  case  the  mortality  was  practically  100  per 
cent.  The  mortality  in  the  case  of  cottonseed  oil  was  0.  Beaumont 
oil,  therefore,  appears  to  be  much  more  effective  than  cottonseed  oil 
in  closing*  the  spiracles,  although  it  should  be  borne  in  mind  that 
there  may  be  a  toxic  effect  that  entered  into  the  results.  It  is  evident 
that  Beaumont  oil  does  not  close  the  spiracles  as  effectually  as  Canada 
balsam. 

The  percentage  of  ticks  in  the  lots  treated  with  Beaumont  oil  that 
oviposited,  compared  with  the  percentage  in  the  corresponding  con- 
trols, is  as  follows:  88  per  cent,  control  100  per  cent;  95  per  cent, 
controls  100  per  cent;  95  per  cent,  controls  100  per  cent.  It  appears 
from  this  that  the  treatment  had  a  slight  effect  on  oviposit  ion.  Cot- 
tonseed oil  had  no  effect  on  the  percentage  ovipositing.  The  treat- 
ment in  no  case  had  any  effect  on  the  number  of  eggs  deposited.  The 
percentage  of  eggs  that  hatched  in  the  case  of  the  ticks  treated  with 
Beaumont  oil,  compared  with  the  percentage  in  the  corresponding 
control  lots,  is  as  follows:  25  per  cent,  control  30  per  cent;  7  per  cent. 
controls  60  and  92  per  cent ;  and  20  per  cent,  controls  80  and  92  per 
cent.  From  this  it  appears  that  the  Beaumont  oil  applied  to  the 
spiracles  must  have  been  absorbed  to  some  extent  and  by  this  means 
exerted  a  detrimental  influence  on  the  eggs. 

The  percentage  of  eggs  hatching  in  the  case  of  ticks  treated  with 
cottonseed  oil,  compared  with  that  of  the  corresponding  controls,  is 
as  follows:  92  per  cent,  controls  60  and  92  per  cent;  and  90  per  cent, 
controls  80  to  92  per  cent.  It  is  therefore  noted  that  .cottonseed  oil 
had  no  influence  on  the  eggs. 


12  ACTION   OF   ARSENICAL   DIPS  AGAINST  CATTLE   TICKS. 

SMEARING  THE  SCUTUM   AND  MOUTH   PARTS. 

In  order  to  determine  whether  the  presence  of  an  oil  or  viscous 
substance  on  the  scutum  and  mouth  parts  would  interfere  with  ovipo- 
sition  and  the  laying  of  normal  eggs,  a  number  of  tests  were  made. 
On  June  8,  1911,  10  engorged  females  that  had  already  begun  to 
oviposit  were  smeared  on  the  scutum  and  mouth  parts  with  Beaumont 
oil.  Eight  of  the  ticks  died.  All  but  one  of  the  ticks  deposited 
some  eggs.  Only  a  few  eggs  were  deposited,  none  of  wThich  hatched. 
In  the  control  lot  of  10  ticks,  6  died.  All  oviposited.  A  moderate 
number  of  eggs  were  deposited,  none  of  which  hatched. 

On  June  8,  1911,  10  engorged  ticks  that  had  begun  to  oviposit  were 
similarly  smeared  with  Canada  balsam.  All  but  one  oviposited. 
Eight  ticks  died.  A  moderate  number  of  eggs  were  deposited,  less 
than  1  per  cent  of  which  hatched.  In  the  control  lot  of  ticks,  six  died. 
All  oviposited.  A  moderate  number  of  eggs  were  deposited,  none 
of  which  hatched. 

On  June  8,  1911,  10  engorged  females  that  had  begun  to  oviposit 
were  smeared  on  the  scutum  and  mouth  parts  with  pine  tar.  All 
the  ticks  oviposited.  Eight  died.  A  considerable  number  of  eggs 
were  deposited,  10  per  cent  of  which  hatched.  In  the  control  lot,  con- 
sisting of  10  ticks.  6  died.  All  oviposited.  A  moderate  number  of 
eggs  were  deposited,  none  of  which  hatched. 

September  27,  1912,  20  engorged  females  just  collected  were  simi- 
larly smeared  with  crude  Beaumont  oil.  All  oviposited.  A  normal 
number   of  eggs  were  deposited.     Fifty  per  cent  of  the  eggs  hatched. 

On  September  27,  1912,  20  engorged  females  just  collected  were 
smeared  on  the  scutum  and  mouth  parts  with  refined  cottonseed  oil. 
One  tick  became  discolored.  Two  more  ticks  became  discolored 
shortly  before  oviposition  was  completed.  All  oviposited.  A  normal 
number  of  eggs  wTere  deposited,  and  87  per  cent  of  the  eggs  hatched. 

On  September  27,  1912,  20  engorged  females  just  collected  were 
similarly  smeared  with  Canada  balsam.  All  oviposited.  A  usual 
number  of  normal  eggs  were  deposited.  Seventy-five  per  cent  of 
the  eggs  hatched. 

In  two  control  lots  of  20  ticks  each,  collected  on  the  same  date  as 
the  above,  none  died.  All  oviposited.  A  normal  number  of  eggs 
were  deposited ;  92  and  60  per  cent  of  the  eggs  hatched. 

On  September  27, 1912,  the  scutum  and  mouth  parts  of  20  engorged 
females  just  collected  were  smeared  with  crude  Beaumont  oil.  One 
tick  (5  per  cent)  died  and  one  became  abnormal  in  appearance.  All 
but  one  oviposited.  A  normal  number  of  eggs  were  deposited. 
Eighty-five  per  cent  of  the  eggs  hatched. 

On  September  28,  1912,  the  scutum  and  mouth  parts  of  20  engorged 
females  collected  on  the  previous  day  were  smeared  with  refined 


HOW   DIPS   ACT  ON   TICKS. 


13 


cottonseed  oil.  Five  ticks  (25  per  cent)  died.  Sixteen  ticks  ovipos- 
ited. A  normal  number  of  eggs  were  deposited.  Ninety-five  per 
cent  of  the  eggs  hatched. 

September  29,  1912,  the  scutum  and  mouth  parts  of  20  engorged 
females  collected  on  September  27  were  smeared  with  Canada  bal- 
sam. All  the  ticks  lived  and  oviposited.  A  usual  number  of  normal 
eggs  were  deposited.     Fifty  per  cent  of  the  eggs  hatched. 

In  two  control  lots  of  20  ticks  each,  collected  on  the  same  date  as 
the  above,  none  died.  All  oviposited  and  a  normal  number  of  eggs 
were  deposited;  92  and  80  per  cent  of  the  eggs  hatched. 

aS' iimm a ry  of  tests  in  which  the  scutum  and  month   part*  of  engorged  females 

were  smeared  with   oils. 


Date  of  test. 

Mortal- 
ity. 

Ticks  ovi- 
positing. 

Number  of  eggs 
deposited. 

Eggs 
hatched. 

Substance  used. 

1911. 
June  R                   

Per  cent. 
80 
60 
80 
60 
80 
60 

Per  cent. 

90 
100 

90 
100 
100 
100 

100 
100 
100 
100 
100 
95 
80 
100 
100 
100 

A  few 

Per  cent. 
0 
0 

(,)» 

10 
0 

50 
87 
75 
92 
60 
85 
95 
50 
92 
80 

Beaumont  oil. 

Do 

Moderate 

(Control.) 
Canada  balsam. 

Do 

do 

Do 

do 

(Control.) 

Do 

Considerable 

Moderate 

Pine  tar. 

Do 

(Control.) 

1912. 

Normal 

Beaumont  oil. 

Do 

20 

0 

0 
0 

35 

25 
0 
0 
0 

do 

Cottonseed  oil. 

Do 

do 

Canada  balsam. 

Do 

do 

(Control.) 
Do. 

Do 

do 

Do 

do 

do 

do 

September  29 

Canada  balsam. 

September  27 

do 

(Control.) 
Do. 

Do 

do... 

1  Less  than  1  per  cent. 

2  Three  (15  per  cent)  became  discolored. 

3  One  more  (5  per  cent)  became  abnormal  in  appearance. 

In  the  tests  in  the  above  table,  started  on  June  8,  1911,  the  high 
mortality  of  the  ticks  was  no  doubt  due  to  the  fact  that  they  had 
been  sent  in  from  the  South  and  in  consequence  had  been  injured  to 
a  certain  extent.  A  comparison  of  the  mortality  of  the  treated  ticks 
with  that  of  the  corresponding  controls  indicates  that  the  treatment 
pla}^ed  no  important  part,  if  any,  in  determining  the  percentage  of 
mortality.  It  is  likewise  apparent  that  the  treatment  had  practically 
no  influence  on  the  number  ovipositing  and  on  the  number  of  eggs 
deposited,  and,  so  far  as  can  be  determined,  the  same  seems  to  be 
true  with  regard  to  the  viability  of  the  eggs. 


DIPPING  THE  TICKS    IN   OILS. 


A  number  of  tests  were  made  in  which  ticks  were  dipped  in  crude 
Beaumont  oil  and  in  refined  cottonseed  oil. 

On  September  27,  1912,  20  engorged  females  just  collected  were 
dipped  in  crude  Beaumont  oil.     Eleven   (12?)    oviposited.     Eight 


14 


ACTION    OF   ARSENICAL  DIPS  AGAINST   CATTLE   TICKS. 


(40  per  cent)  died.  Only  a  small  number  of  eggs  were  deposited, 
part  of  which  shriveled.    Less  than  1  per  cent  of  the  eggs  hatched. 

On  September  27,  1912,  20  engorged  females  just  collected  were 
dipped  in  refined  cottonseed  oil.  One  tick  (5  per  cent)  died.  All 
oviposited.  A  normal  number  of  eggs  were  deposited.  Ninety  per 
cent  of  the  eggs  hatched. 

In  two  control  lots  collected  on  September  27,  consisting  of  20 
ticks  each,  none  died.  All  oviposited  and  a  normal  number  of  eggs 
were  deposited ;  92  and  60  per  cent  of  the  eggs  hatched. 

September  27, 1912,  20  engorged  females  just  collected  were  dipped 
in  Beaumont  crude  petroleum.  Thirteen  ticks  (65  per  cent)  ovi- 
posited. Eight  ticks  (40  per  cent)  died.  Several  others  became 
abnormal  in  appearance.  Only  a  few  eggs  were  deposited,  about 
half  of  which  shriveled.    Less  than  1  per  cent  of  the  eggs  hatched. 

September  28,  1912,  20  engorged  females  collected  the  previous  day 
were  dipped  in  refined  cottonseed  oil.  All  but  one  tick  remained 
normal.  A  normal  number  of  eggs  were  deposited,  some  of  which 
shriveled.    Eighty-five  per  cent  of  the  eggs  hatched. 

In  two  control  lots  of  20  ticks  each,  collected  on  September  27, 
1912,  all  oviposited.  A  normal  number  of  eggs  were  deposited;  92 
and  80  per  cent  of  the  eggs  hatched. 

Summary  of  tests  in  which  engorged  tides  were  dipped  in  oils. 


Date  of  test. 


Mor-      Ticks  ovi-i      Number  of  eggs 
tality.    I  positing.  |  deposited. 


Eggs 
hatched. 


Oil  used. 


September  27, 1912. 

Do 

Do 

Do 

Do 

September  28,  1912 
September  27,  1912 

Do 


Per  cent. 

Per  cent. 

40 

55 

5 

100 

0 

100 

0 

100 

2  40 

65 

30 

0 

100 

0 

100 

Small.. 
Normal 
....do. 
....do. 
Few.. . 
Normal 
....do. 
....do. 


Beaumont  oil. 
Cottonseed  oil. 
(Control.) 

Do. 
Beaumont  oil. 
Cottonseed  oil. 
(Control.) 

Do. 


1  Less  than  1  per  cent, 
a  i )  tliers  became  abnormal  in  appearance. 
<  'lie  tick  (5  per  cent)  became  abnormal  in  appearance. 

In  the  foregoing  table  it  is  noted  that  the  mortality  in  the  case  of 
ticks  dipped  in  Beaumont  oil  was  40  per  cent  in  both  tests,  and  in  the 
case  of  ticks  dipped  in  cottonseed  oil  it  was  5  per  cent  and  0  per  cent. 
Beaumont  oil  is  therefore  shown  to  have  a  greater  destructive  action 
than  cottonseed  oil,  and  this  is  probably  due  largely  to  a  toxic  action 
of  some  kind,  since  in  the  tests  in  which  the  spiracles  were  touched 
with  Beaumont  oil  this  oil  was  shown  to  be  much  less  effective  than 
in  the  present  tests.  Beaumont  oil  reduced  the  percentage  of  females 
ovipositing  and  the  number  of  eggs  deposited.  Cottonseed  oil  had 
no  influence  on  oviposition  or  on  the  number  of  eggs  deposited.  The 
percentage  of  eggs  hatching  in  the  case  of  the  ticks  dipped  in  Beau- 


HOW   DIPS  ACT   OX    TICKS.  15 

mont  oil  was  very  low — less  than  1  per  cent — while  the  percentage 
hatching  in  the  case  of  those  clipped  in  cottonseed  oil  was  practically 
normal.  This  would  seem  to  be  further  evidence  of  the  absorption 
of  Beaumont  oil  and  its  toxicity,  although  it  should  be  stated  that  it 
is  likely  that  a  part  of  the  lack  of  viability  may  have  been  due  to  the 
eggs  coming  directly  in  contact  with  the  oil  on  the  bodies  of  the  ticks. 

THE  EFFECT  OF  ARSENIC   ON   TICKS. 

Arsenic  acts  on  ticks  entirely  as  a  result  of  its  toxic  properties. 
The  avenues  by  which  the  arsenic  gains  entrance  to  the  bodies  of 
ticks  have  not  been  determined.  As  pointed  out  in  Bulletin  144, 
Bureau  of  Animal  Industry,  the  possible  ways  are  (1)  through  the 
mouth;  (2)  through  the  breathing  pores:  (3)  through  other  open- 
ings of  the  body ;  or  (4)  by  absorption  through  the  cuticle.  Arsenic 
in  entering  by  way  of  the  mouth  may  enter  in  two  ways,  namely, 
directly,  or  indirectly  through  the  blood  or  lymph.  Under  other 
openings  of  the  body  may  be  mentioned  the  anus,  the  genital  pore  in 
adult  ticks,  the  cephalic  gland  in  the  female  and  nymph,  and  glan- 
dular openings  in  the  cuticle. 

It  is  not  likely  that  any  dip  enters  the  body  through  the  anus  or 
genital  openings,  as  these  are  kept  tightly  closed.  The  cephalic 
gland,  located  beneath  the  scutum  and  having  its  opening  situated 
in  the  soft  chitin  between  the  scutum  and  the  base  of  the  rostrum, 
offers  a  possible  point  of  entrance.  This  gland  secretes  a  viscous 
fluid  which  causes  the  eggs  to  adhere  together  and  protects  them  from 
loss  of  moisture  by  evaporation.  Anything  that  would  interfere 
with  the  function  of  this  gland  would  affect  materially  the  viability 
of  the  eggs  deposited.  The  openings  of  the  tegumentary  glands, 
which  are  numerous,  furnish  another  means  of  entrance  of  arsenic 
through  the  chitinous  covering  of  the  body. 

The  porose  areas,  two  in  number,  located  on  the  dorsal  side  of  the 
base  of  the  rostrum,  furnish  another  possible  point  of  entrance  in  the 
case  of  adult  females.  According  to  Bonnet x  the  punctations  of 
these  areas  are  pores  passing  through  the  chitin.  each  of  which  com- 
municates with  an  exposed  nerve  cell  lying  beneath  the  chitinous  cov- 
ering, and  which  is  the  termination  of  one  of  the  fibers  of  a  nerve 
adjacent  to  the  area.  As  these  nerve  cells  are  without  cell  membranes 
and  are  unprotected  in  any  way.  it  would  appear  that  the  porose 
areas  constitute  a  most  vulnerable  point  in  the  body  of  the  tick  for 
the  entrance  of  arsenic. 

1  Bonnet,  Am&lee.  Reeherches  gur  1'anatomie  comparee  et  le  d€veloppement  di  s 
ixodides.     Annales  de  rUniversite  de  Lyon,  n.  s.,  I  :  sc.  nied.,  fasc.  20.     Lyon  and  Paris. 


16  ACTIOX    OF   ARSENICAL   DIPS   AGAINST   CATTLE    TICKS. 

CATTLE-DIPPING   EXPERIMENTS  TO  ASCERTAIN  THE    PROTECTIVE 
ACTION  OF  ARSENICAL  DIPS. 

EXPERIMENT  NO.  1. CATTLE  EXPOSED  TO  INFESTATION  AT  VARIOUS  INTER- 
VALS   FROM    A    FEW    HOURS   TO   FOUR  AVEEKS   AFTER   DIPPING. 

In  this  experiment  the  arsenical  dip  used  was  made  on  April  9, 1912. 
No  pine  tar  was  used,  for  the  purpose  of  avoiding  any  repellent 
action  that  it  might  contribute  to  the  dip.  The  dip  was  made  in  the 
usual  way,  the  formula  being  8  pounds  arsenic  trioxid  and  24  pounds 
of  sodium  carbonate  to  500  gallons  of  dip.  Samples  of  the  dip  were 
taken  on  three  dates  for  analysis.     The  analyses  x  follow : 

Analyses  of  arsenical  dip  used  in   experiment  No.   I. 

Actual    I     Total 
AsoG3.    I    As20,. 


1912.                                                                           Percent.  Percent. 

Apr.  29 0. 1847  0. 1851 

May  10 1841  .  1901 

June  20 1229  .  2022 


It  is  seen  that  at  the  time  of  the  first  dipping  there  was  present 
in  the  bath  0.1847  per  cent  of  As203  and  a  total  amount  of  arsenic 
equivalent  to  0.1851  per  cent  of  arsenic  trioxid.  and  on  June  20,  two 
days  after  the  last  dipping,  0.1229  per  cent  of  As203  and  a  total 
amount  equivalent  to  0.2022  per  cent  arsenic  trioxid.  The  actual 
amount  of  As203  present  had  decreased  during  the  course  of  the  dip- 
ping about  one-third  through  oxidation,  and  the  percentage  of  total 
arsenic  had  increased  slightly  as  a  result  of  evaporation. 

Each  animal  was  kept  in  the  dip  two  minutes. 

There  were  12  animals  (calves)  in  the  experiment,  all  being  north- 
ern cattle  (nonimmune).  Each  animal  was  infested  with  the  seed 
ticks  hatched  from  2 J  grams  of  eggs.  The  seed  ticks  used  were  the 
progeny  of  engorged  females  (Margaropus  annulatus)  collected  at 
Fori  Worth,  Tex.,  May  3,  1912. 

Previous  to  the  time  the  calves  were  infested  they  were  kept  in  a 
yard  provided  with  shelter,  which  they  might  seek  when  they  desired. 
On  the  day  of  infestation  (June  18)  they  were  removed  to  another 
yard  where  there  was  no  shelter  and  kept  there  until  the  following 
noon,  when  they  were  placed  under  cover,  where  they  remained  until 
the  close  of  the  experiment.  During  the  night  and  the  forenoon  fol- 
lowing infestation  the  animals  were  out  in  a  light  rain. 

Lot  1.  Calve*  Nos.  9%2  and  .9.'/?.— June  18.  1912,  the  calves  were  dipped  once  in 
an  arsenical  dip  containing  a  total  amount  of  arsenic  equivalent  to  0.2022  per 
cent  As203  and  containing  arsenic  in  the  form  of  As/):,  to  the  extent  of  0.1220 

1  All  analyses  referred  to  in  this  bulletin  were  made  by  the  Biochemic  Division  of  the 
Bureau  of  Animal   Industry. 


THE   PROTECTIVE   ACTION    OF    ARSENICAL   DIPS.  17 

per  cent.  Each  calf,  as  soon  as  dry,  was  infested  with  seed  ticks.  They  were 
kept  under  observation  until  July  22.  No  tk-ks  developed,  and  there  was  no 
fever. 

Lot  2.  Calves  Xos.  939  and  9^1. — The  calves  were  dipped  four  times  at  inter- 
vals of  two  weeks,  on  May  7  and  21.  and  June  4  and  18,  in  an  arsenical  dip. 
They  were  infested  with  seed  ticks  on  the  date  of  the  last  dipping  as  soon  as 
they  were  dry-  They  were  under  observation  until  July  22.  No  ticks  developed, 
and  there  was  no  fever. 

Lot  Jh  Calves  Noe.  940  ond  9.'1'h — These  were  dipped  four  times  at  intervals  of 
two  weeks  (April  30.  May  14  and  28,  and  June  11)  in  an  arsenical  dip.  On 
June  18.  one  week  after  the  last  dipping,  they  were  infested  with  seed  ticks. 
Both  animals  became  infested  with  ticks  and  developed  Texas  fever.  Calf  940 
died  of  the  fever  July  9.  This  animal  became  heavily  infested  with  ticks,  and 
at  the  time  of  death  most  of  the  ticks  had  molted  the  second  time.  A  few 
r.ymphs  were  present.  The  adult  ticks  ranged  from  those  just  molted  to  some 
about  one-third  engorged.  Calf  944  became  only  lightly  infested  with  ticks. 
Nine  hundred  and  six  adult  ticks  were  collected,  the  last  ones  being  removed  on 
July  30.     The  animal  recovered  from  the  fever. 

Lot  5.  Calves  Xos.  948  and  9.^9. — These  were  dipped  in  an  arsenical  dip  four 
times  at  intervals  of  two  weeks,  on  April  23.  May  7  and  21,  and  June  4.  Two 
weeks  following  the  last  dipping,  that  is,  on  June  IS,  they  were  infested  with 
seed  ticks.  Both  contracted  Texas  fever,  and  No.  948  died  July  11.  This  calf 
became  moderately  infested  with  ticks.  At  the  time  of  death  most  of  the  ticks 
were  in  the  adult  stage  and  ranged  from  the  newly  molted  to  the  engorged 
condition.  Calf  949  became  heavily  infested  with  ticks.  The  last  adults  were 
removed  August  1.     In  all,  4,884  ticks  were  collected  from  this  animal. 

Lot  6.  Calves  Xos.  9.'f3  and  9'f5. — This  lot  was  dipped  four  times  (April  9  and 
23.  May  7  and  21),  at  intervals  of  two  weeks,  in  an  arsenical  dip.  Four  weeks 
after  the  last  dipping  (June  18)  they  were  infested  with  seed  ticks.  Calf  943 
became  heavily  infested  with  ticks  and  calf  945  acquired  a  moderate  infestation. 
Both  contracted  Texas  fever,  and  calf  945  died  July  8.  The  stages  present  were 
r.yinphs  and  young  adults.  In  the  case  of  calf  943  the  last  tick  was  collected 
on  August  3,  and  in  all  5,715  ticks  were  removed. 

Lot  3  (control).  Cains  Xos.  OJ/6  and  950. — These  animals  were  not  dipped. 
They  were  infested  with  seed  ticks  on  the  same  date  as  the  other  lots  (June  18). 
Both  animals  became  heavily  infested  with  ticks  and  contracted  Texas  fever. 
Calf  946  died  July  6.  It  was  heavily  infested  with  nymphs  and  young  adults. 
Calf  950  was  nearly  dead  July  15  and  was  killed.  Up  to  the  time  the  animal 
was  killed.  2,960  adult  ticks  had  been  collected. 

OBSERVATIONS    OX    ENGORGED     TICKS     REMOVED    FROM     THE    ANIMALS. 

These  ticks  were  kept  in  Petri  dishes. 

Ticks  removed  from  calf  9't.'f  (lot  h). — July  12,  70  engorged  and  nearly  en- 
gorged ticks  removed.  All  but  one  of  the  ticks  deposited  eggs.  A  good  many 
eggs  shriveled.  Most  of  the  ticks  died  either  without  ovipositing  or  before  ovi- 
position  was  completed.    About  60  per  cent  of  the  eggs  hatched. 

July  15,  13  engorged  ticks  removed.  All  but  one  oviposited.  Some  eggs 
shriveled.  Thirty-one  per  cent  of  the  ticks  died  either  without  ovipositing  or 
before  oviposition  was  completed.    About  10  per  cent  of  the  eggs  hatched. 

July  16,  55  engorged  and  nearly  engorged  ticks  removed.  All  oviposited  ex- 
cept four.  Sixty-four  per  cent  of  the  ticks  died  either  without  ovipositing  or 
before  oviposition  was  completed.     About  95  per  cent  of  the  eggs  hatched. 


18  ACTION   OF   ARSENICAL  DIPS  AGAINST   CATTLE    TICKS. 

July  17,  15  engorged  ticks  removed  for  study.  All  oviposited.  Seventy-three 
per  cent  of  the  ticks  died  before  oviposition  was  completed.  About  10  per  cent 
of  the  eggs  hatched. 

July  18,  20  engorged  females  removed.  All  oviposited.  Sixty  per  cent  died 
before  oviposition  was  completed.    About  50  per  cent  of  the  eggs  hatched. 

July  19,  25  engorged  and  nearly  engorged  ticks  removed.  All  but  one  ovi- 
posited. Small  number  of  eggs  deposited.  Eggs  were  scattered  and  many 
shriveled.  Twenty-four  per  cent  of  the  ticks  died  either  without  ovipositing  or 
before  oviposition  was  completed.     Less  than  1  per  cent  of  the  eggs  hatched. 

Ticks  removed  from  calf  9Jt9  (lot  5). — July  12,  removed  336  engorged  and 
nearly  engorged  ticks.  Lot  No.  1  of  100  ticks:  All  but  two  oviposited.  About 
half  of  the  ticks  died  either  without  ovipositing  or  before  oviposition  was  com- 
pleted. About  95  per  cent  of  the  eggs  hatched.  Lot  No.  2  of  100  ticks:  All  but 
one  oviposited.  About  50  per  cent  of  the  ticks  died  either  without  ovipositing 
or  before  oviposition  was  completed.  About  95  per  cent  of  the  eggs  hatched. 
Lot  No.  3  of  136  ticks :  All  but  three  oviposited.  About  half  of  the  ticks  died 
either  without  ovipositing  or  before  oviposition  was  completed.  About  90  per 
cent  of  the  eggs  hatched. 

July  15,  removed  49  engorged  ticks.  All  oviposited.  About  33  per  cent  of  the 
ticks  died  before  oviposition  was  completed.  About  95  per  cent  of  the  eggs 
hatched. 

July  16,  removed  119  engorged  females.  All  but  six  oviposited.  About  65 
per  cent  of  the  ticks  died  either  without  ovipositing  or  before  oviposition  was 
completed.    About  85  per  cent  of  the  eggs  hatched. 

July  17,  removed  30  engorged  ticks.  All  oviposited.  About  30  per  cent  died 
before  oviposition  was  completed.     About  90  per  cent  of  the  eggs  hatched. 

July  18.  removed  30  engorged  females.  All  oviposited  but  one.  Forty-three 
per  cent  died  either  without  ovipositing  or  before  oviposition  was  completed. 
About  95  per  cent  of  the  eggs  hatched. 

July  19,  removed  118  engorged  and  nearly  engorged  females.  All  oviposited. 
About  33  per  cent  died  before  oviposition  was  completed.  About  90  per  cent  of 
the  eggs  hatched. 

Ticks  removed  from  calf  943  (lot  6). — July  12,  removed  200  engorged  and 
nearly  engorged  ticks.  Lot  No.  1  of  100  ticks:  All  but  five  ticks  oviposited. 
About  65  per  cent,  of  the  ticks  died  either  without  ovipositing  or  before  oviposi- 
tion was  completed.  About  95  per  cent  of  the  eggs  hatched.  Lot  No.  2  of  100 
ticks :  All  oviposited.  About  half  of  the  ticks  died  before  oviposition  was  com- 
pleted.    About  95  per  cent  of  the  eggs  hatched. 

July  15,  removed  35  engorged  ticks.  All  oviposited  but  one.  More  than  half 
of  the  ticks  died  either  without  ovipositing  or  before  oviposition  was  completed. 
About  95  per  cent  of  the  eggs  hatched. 

July  16,  removed  116  ticks.  All  but  five  oviposited.  About  half  of  the  ticks 
died  either  without  ovipositing  or  before  oviposition  was  completed.  About  95 
per  cent  of  the  eggs  hatched. 

July  17,  removed  20  engorged  females.  All  oviposited.  Thirty  per  cent  of 
the  ticks  died  before  oviposition  was  completed.  About  25  per  cent  of  the  eggs 
hatched. 

July  is.  removed  30  engorged  ticks.  All  but  one  oviposited.  Ten  per  cent  of 
the  ticks  died  either  without  ovipositing  or  before  oviposition  was  completed. 
About  75  per  cent  of  the  eggs  hatched. 

July  19,  removed  49  engorged  and  nearly  engorged  females.  All  but  one  ovi- 
posited. Fourteen  per  cent  of  the  ticks  died  either  without  ovipositing  or  before 
oviposition  was  completed.    About  50  per  cent  of  the  eggs  hatched. 

Ticks  removed  from  calf  950  (lot  3,  control). — July  12,  removed  200  engorged 
and  nearly  engorged  ticks.    Lot  No.  1  of  100  ticks :  All  oviposited.    Ninety-seven 


THE   PROTECTIVE  ACTION    OF  ARSENICAL  DIPS.  19 

per  cent  of  the  ticks  died  before  oviposition  was  completed.  About  90  per  cent 
of  the  eggs  hatched.  Lot  No.  2  of  100  ticks :  All  but  one  oviposited.  Ninety- 
five  per  cent  of  the  ticks  died  either  without  ovipositing  or  before  oviposition 
was  completed.    About  90  per  cent  of  the  eggs  hatched. 

July  15,  removed  26  engorged  and  nearly  engorged  ticks.  All  but  one  ovi- 
posited. Most  of  the  ticks  died  either  without  ovipositing  or  before  oviposition 
was  completed.    About  90  per  cent  of  the  eggs  hatched. 

« 

DISCUSSION   OF   RESULTS. 

Effect  on  the  animals. — It  is  noted  from  the  above  results  that 
cattle  dipped  four  times  at  intervals  of  two  weeks  in  an  arsenical 
dip  (lot  2)  and  subjected  to  infestation  as  soon  as  dry  following  the 
last  dipping  vrere  protected  from  infestation.  It  was  found  that  cat- 
tle dipped  only  once  (lot  1)  and  subjected  to  infestation  as  soon  as 
dry  were  likewise  protected  from  infestation.  It  is  therefore  seen 
that  arsenic  absolutely  protected  animals  from  infestation  when  ex- 
posed immediately  following  a  dipping  and  that  one  dipping  was 
just  as  effective  in  producing  this  result  as  a  number  of  dippings  at 
intervals  of  two  weeks.  Since  none  of  the  animals  contracted  Texas 
fever,  we  are  led  to  conclude  that  the  ticks  failed  to  infect  the  ani- 
mals before  they  were  killed  by  the  arsenic. 

It  was  also  found  that  cattle  dipped  four  times  at  intervals  of  two 
weeks  and  infested  one  (lot  4),  two  (lot  5),  and  four  weeks  (lot  6) 
after  the  last  dipping,  became  infested  with  ticks  and  all  contracted 
Texas  fever.  Of  the  six  animals  in  these  lots,  three  (50  per  cent) 
died  of  fever,  whereas,  as  already  mentioned,  there  was  no  fever  or 
deaths  in  the  lots  infested  immediately  after  dipping.  In  the  control 
lot  (lot  3)  both  animals  became  infested  with  ticks  and  died  of 
Texas  fever. 

Effect  on  the  ticks. — Observations  were  made  from  time  to  time  on 
the  animals  for  the  purpose  of  noting  any  ticks  that  might  show 
evidence  of  arsenical  poisoning.  Only  a  very  few  dead  and  abnor- 
mal ticks  were  found.  A  few  dead  females  were  noted  on  calf  949, 
a  good  many  abnormal  young  females,  and  a  few  dead  ticks  on 
calf  943,  and  some  abnormal  young  females  on  calf  945.  It  is  possi- 
ble that  these  ticks  were  affected  by  arsenic  absorbed  from  the  skin 
of  the  animal,  but  their  number,  compared  with  the  total  number  of 
ticks  present,  was  so  small  that  it  may  be  said  that  the  arsenic,  if 
active  at  all.  had  a  negligible  effect  on  the  nymphal  and  adult  stages 
of  the  tick.  Whether  this  was  also  true  of  the  larval  stage  of  the 
tick  can  not  be  said,  since  it  was  not  practicable  to  make  observations 
on  this  stage  on  account  of  their  small  size  and  the  difficulty  in  find- 
ing them. 

An  interesting  abnormality  was  found  in  some  engorged  females 
taken  from  two  of  the  dipped  animals.  Ten  of  them  were  taken  from 
calf  949  and  one  from  calf  943.     These  ticks  were  plump  and  trans- 


20 


ACTION   OF   ARSENICAL   DIPS  AGAINST   CATTLE    TICKS. 


parent.  The  dark  intestinal  branches  and  the  Malphigian  tubes 
could  be  plainly  seen  lying  in  the  lower  portion  of  the  body  cavity. 
On  puncturing  the  body  wall  a  clear  fluid  issued  from  the  body 
cavity.  Five  of  the  ticks  from  calf  949  were  set  aside  for  special 
observation.  All  began  ovipositing,  but  egg-laying  progressed  very 
slowly  and  only  a  few  eggs  were  deposited.  None  of  the  eggs 
hatched,  although  some  of  them  developed  nearly  to  the  point  of 
hatching. 

Nothing  final  was  determined  with  regard  to  whether  there  is  any 
relation  between  the  number  of  ticks  developing  on  animals  and  the 
duration  of  the  interval  elapsing  between  the  last  dipping  and  the 
date  of  infestation. 

For  the  purpose  of  obtaining  data  on  this  point  approximately  the 
same  number  of  ticks  were  placed  on  all  the  cattle — that  is.  larva? 
that  hatched  from  2^  grams  of  eggs.  In  the  case  of  the  two  animals 
infested  one  week  after  the  last  dipping  (lot  4),  one  became  heavily 
infested  and  the  other  lightly  infested ;  in  the  case  of  those  infested 
two  weeks  after  the  final  dipping  (lot  5),  one  became  moderately 
infested  and  the  other  heavily  infested;  and  in  the  case  of  the  two 
animals  infested  four  weeks  after  the  last  dipping  (lot  6),  the  result 
was  the  same,  one  becoming  heavily  infested  and  the  other  moder- 
ately infested.  The  two  control  animals  became  heavily  infested 
with  ticks. 

An  attempt  was  made  to  obtain  additional  and  more  definite  in- 
formation on  the  above  point  by  collecting  as  far  as  possible  all  the 
engorged  ticks  maturing  on  the  animals.  This  was  interfered  with, 
however,  by  the  death  of  five  of  the  eight  animals  that  became  in- 
fested, including  the  two  control  animals.  The  results  from  the 
three  animals  that  survived  are  as  follows : 

Number  of  engorged  female  ticks  collected  from  surviving  animals. 


Interval 

between 

Number  of 

No.  of 

last  dip- 

engorged 

animal. 

ping  and 

females 

infestation 

collected. 

(weeks). 

944 

! 

906 

949 

2 

4,884 

943 

4 

5,715 

While  it  would  appear  from  this  that  the  infestation  becomes  in- 
tensified as  the  interval  increases  following  the  last  dipping,  the 
data  are  not  adequate  for  drawing  conclusions  on  this  point. 

The  observations  made  on  the  engorged  females  removed  at  inter- 
vals from  the  animals  (p.  17)  were  for  the  purpose  of  determining 
whether  any  arsenic  absorbed  by  the  tick  might  destroy  it  after  it 


THE   PROTECTIVE  ACTION    OF   ARSENICAL  DIPS. 


21 


had  dropped  from  the  host,  or,  failing  this,  whether  it  would  in- 
fluence oviposition  or  affect  the  viability  of  the  eggs. 

The  results  on  mortality  obtained  from  the  ticks  collected  from 
four  animals  are  as  follows : 

Lot  4  (calf  944),  about  50  per  cent  died. 
Lot  5  (calf  949),  about  40  per  cent  died. 
Lot  6  (calf  943),  about  50  per  cent  died. 
Lot  3  (calf  950,  control),  about  95  per  cent  died. 

It  is  noted  that  the  mortality  of  the  ticks  from  the  undipped  con- 
trol animal  is  higher  than  for  the  dipped  animals.  The  mortality 
in  all  cases  is  abnormally  high  and  is  very  likely  due  to  the  fact  that 
all  of  the  animals  suffered  from  Texas  fever,  and  this,  either  because 
of  the  well-known  changes  in  the  blood  or  some  other  cause,  such  as, 
for  example,  an  excessive  invasion  with  Piroplasrwa  bigeminum, 
had  a  deleterious  effect  on  the  ticks.  The  results,  therefore,  do  not 
make  it  possible  to  draw  any  conclusions  with  regard  to  what  part, 
if  any,  arsenic  played  in  the  mortality. 

After  obtaining  the  above  results  the  writer  made  some  observa- 
tions on  engorged  females  collected  from  undipped  animals  suffering 
from  Texas  fever  in  an  experiment  conducted  by  Drs.  Schroeder  and 
Cotton,  of  the  Bureau  of  Animal  Industry.  The  data  obtained  from 
these  ticks  are  as  follows : 

Mortality  of  engorged  ticks  collected  from  animals  suffering  from  Texas  fever. 


No.  of 
animal. 

Number 
of  ticks  re- 
moved. 

Mortality. 

808 
792 

684 
803 
742 

1,277 
665 
978 
579 
372 

Per  cent. 
10 
12 
7 
17 
32 

The  mortality  here  is  not  nearly  as  high  as  in  the  above  instances. 
Unfortunately,  no  ticks  from  animals  not  suffering  from  fever  were 
available  for  controls,  but  it  is  known  as  the  result  of  a  wide  experi- 
ence with  ticks  from  normal  animals  that  the  mortality  is  abnormally 
high. 

The  percentage  of  the  engorged  females  that  oviposited  is  given 
in  the  following  table.  The  ticks  were  collected  from  each  animal 
from  July  12  to  19,  inclusive,  and  kept  under  observation. 

Percentage  of  engorged  tides  ovipositing. 


Number  of  animal  from  which  collected. 


Ticks  ovi- 
positing. 


944  (lot  4) 

949  (lot  5) 

943  (lot  6) 

950  (lot  3,  control) 


Per  cent. 


22 


ACTION    OF   ARSENICAL   DIPS   AGAINST    CATTLE    TICKS. 


It  is  noted  from  the  above  table  that  the  ticks  ovipositing  from 
the  dipped  animals  range  from  1  to  3  per  cent  lower  than  those 
from  the  undipped  animal  (control).  This  difference,  however,  is 
so  slight  as  to  have  no  significance,  and  it  may  be  concluded  that 
any  arsenic  absorbed  by  the  ticks  failed  to  be  sufficiently  active  to 
prevent  oviposition. 

The  percentage  of  eggs  hatched  in  the  case  of  the  various  lots  of 
ticks  collected  from  animals  that  survived  long  enough  for  ticks  to 
mature  is  as  follows : 


Percentage  of  eggs  hatching. 


Date  collected. 


Calf  944 
(lot  4). 


Calf  949 
(lot  5). 


Calf  943 
(lot  6). 


Calf  950 

(lot  3, 

control). 


July  12 
Julv  15 
July  16 
July  17 
July  18 
Julv  19 


Per  cent. 
60 
10 
95 
10 
50 
1 


Per  cent. 
95, 95.  and  90 
95 
85 
90 
95 
90 


Per  cent. 

95  and  95 
95 
95 
25 
75 
50 


Per  cent. 
90  and  90 


The  percentage  in  the  three  dipped  animals  (944,  949,  and  943) 
ranged  from  1  to  95,  85  to  95,  and  25  to  95,  respectively,  as  com- 
pared with  90  per  cent  in  the  three  lots  from  the  control  animal. 

Because  of  the  fact  that  it  was  necessary  to  kill  the  only  remaining 
control  animal  (calf  950)  on  July  15,  there  were  no  undipped  ticks 
available  for  comparison  with  those  collected  from  the  dipped  animals 
on  July  16  to  19,  inclusive. 

By  comparing  the  percentages  for  the  dipped  animals  with  those 
of  the  control  for  July  12  and  15,  it  is  noted  that  the  percentage  of 
eggs  hatching  from  ticks  from  calf  941,  infested  one  week  after 
dipping,  is  low.  while  the  percentage  for  each  of  the  other  two 
animals,  infested  two  and  four  weeks  after  dipping,  is  normal.  It 
is  noted  that  in  general  the  percentages  for  the  remaining  dates  range 
lower  for  calf  944  than  for  the  other  animals.  Unfortunately  the 
percentages  for  the  dipped  animals  can  not  be  averaged  for  purposes 
of  comparison,  because  the  number  of  eggs  in  the  different  lots  varied 
greatly. 

It  is  evident,  however,  that  while  arsenic  may  have  been  responsible 
for  a  decrease  in  the  viability  of  the  eggs  in  the  case  of  calf  944,  there 
has  been  no  such  effect  in  the  case  of  the  ticks  from  the  other  two 
dipped  animals,  and,  on  the  whole,  it  seems  safe  to  conclude  that 
arsenic  has  played  no  important  part  in  determining  the  percentage 
of  eggs  that  hatched. 

It  should  be  borne  in  mind  that  this  result  is  not  contrary  to  those 
recorded  in  Bulletin  144  of  the  Bureau  of  Animal  Industry,  where 
ticks  subjected  to  the  direct  influence  of  arsenic  were  found  to  lay  eggs 


THE  PEOTECTIVE  ACTION   OF  AESENICAL  DIPS.  23 

that,  as  a  rule,  did  not  hatch.  The  ticks  in  the  present  tests  were  sub- 
jected only  to  the  indirect  action  of  arsenic,  as  they  were  not  applied 
as  seed  ticks  until  one  to  four  weeks  after  the  animals  were  dipped. 

EXPERIMENT    NO.     2. CATTLE    EXPOSED    TO    INFESTATION    TWO    AND    ONE- 
HALF   HOURS    AND   TWO   DAYS    AFTER    DIPPING. 

After  having  shown  by  experiment  Xo.  1  that  arsenic  has  a  pro- 
tective action  which  lasts  for  less  than  a  week,  it  was  determined  to 
conduct  another  experiment  for  the  purpose  of  determining  the  length 
of  time  that  arsenic  will  protect.  It  was  also  thought  necessary  to 
repeat  the  tests  showing  that  arsenic  protected  against  immediate  in- 
festation, since  there  was  a  possibility  that  the  results  obtained 
might  have  been  accidental.  One  thing  that  threw  doubt  on  the 
last-mentioned  result  was  the  fact  that  the  animals,  following  the 
last  dipping  and  the  infestation  (carried  out  on  the  same  day),  were 
out  in  a  slow  rain,  which  it  was  thought  might  have  kept  the  arsenic 
in  solution  on  the  skin  and  created  a  condition  much  as  if  the  ticks 
had  been  subjected  for  some  hours  to  an  arsenical  dip.  In  order  to 
obviate  this  possibility  in  the  following  experiment,  the  dipped  ani- 
mals, as  soon  as  dry.  were  placed  at  once  under  shelter  and  kept 
there  until  the  close  of  the  experiment. 

In  experiment  Xo.  1  the  animals  were  kept  submerged  in  the  dip 
for  two  minutes.  As  this  is  longer  than  an  animal  remains  in  the  dip 
when  passing  through  the  ordinary  dipping  vat.  it  was  determined  in 
the  following  experiment,  in  addition  to  dipping  animals  for  2 
minutes,  to  dip  others  for  20  seconds,  which  comes  nearer  to  the  time 
required  to  pass  through  a  vat. 

The  dip  used  in  experiment  Xo.  2  was  made  on  July  29.  It  was 
made  according  to  the  usual  formula  of  8  pounds  of  arsenic  to  the 
500  gallons.  An  analysis  of  a  sample  taken  on  the  date  the  dip  was 
made  showed  it  to  contain  0.1652  per  cent  arsenic  trioxid.  As  in 
experiment  Xo.  1,  no  pine  tar  was  used.  Twelve  calves  were  used  in 
the  experiment,  divided  into  five  lots  as  described  below.  All  of  the 
cattle  were  dipped  on  August  1.  Lots  1,  2,  and  5  were  infested  with 
the  progeny  of  female  ticks  collected  at  Fort  Worth.  Tex.,  June  2-1, 
1912.  Lots  3  and  4  were  infested  with  the  progeny  of  females  re- 
ceived from  Fort  Worth,  June  29,  1912. 

Lot  1.  Calves  Xos.  957,  9Jfl,  and  958. — Dipped  two  minutes  in  an  arsenical 
dip.  Infested  with  seed  ticks  two  and  one-half  hours  after  dipping.  No  ticks 
developed.  Calves  957  and  947  developed  no  fever.  Calf  958  showed  a  tem- 
perature and  in  all  probability  had  an  attack  of  Texas  fever.  Calf  947  follow- 
ing dipping  suffered  from  anorexia  and  bloat.  On  August  26  the  animal  de- 
\ eloped  a  gastric  fistula  located  on  the  underside  of  the  abdomen.  Food  and 
drops  of  liquid  were  issuing  from  it.  On  August  li*J  the  animal  was  killed.  The 
fistula  was  found  to  extend  into  the  fourth  stomach.  The  mucous  folds  in  the 
region  of  the  fistula  were  hypertrophied,  hemorrhagic,  and  sloughing  awry. 
This  was  clearly  a  case  of  arsenical  poisoning. 


24  ACTION   OF   ARSENICAL   DIPS  AGAINST   CATTLE    TICKS. 

Lot  2.  Valves  Nos.  927,  939,  and  928. — Dipped  20  seconds  in  an  arsenical  dip. 
Infested  with  seed  ticks  two  and  one-half  hours  after  dipping.  No  ticks  de- 
veloped on  these  animals.  There  was  no  fever.  Calf  939  died  August  20.  On 
post-mortem  there  was  an  enteritis,  principally  of  small  intestine  and  cecum. 
There  was  congestion  of  lungs  and  a  slight  congestion  of  kidneys.  Smears  from 
spleen  and  liver  contained  no  piroplasma. 

Lot  3.  Calves  Nos.  955  and  942. — Dipped  two  minutes  in  an  arsenical  dip. 
Infested  two  days  after  dipping  (August  3)  with  seed  ticks.  No  ticks  de- 
veloped on  these  animals.  Calf  942  showed  a  rise  in  temperature  from  the 
ninth  to  the  twelfth  day  after  infestation.  On  August  6  calf  955  died  of 
arsenical  poisoning.  The  liver  was  yellow  (fatty  degeneration)  and  very 
friable.  There  were  large  hemorrhages  in  the  endocardium  of  the  right  side, 
also  large  hemorrhagic  areas  in  all  four  stomachs.  An  enteritis  was  present. 
There  were  edematous  areas  in  wall  of  stomach  and  intestine.  The  capsule  of 
the  spleen  was  much  injected.  All  blood  vessels  were  injected  and  the  blood 
was  very  dark.    There  were  no  lesions  in  the  mouth. 

Found  a  number  of  larvae  on  the  skin,  all  of  which  were  dead.  Two  of  these 
were  observed  with  certainty  to  be  attached. 

Lot  4.  Calves  Nos.  956  and  9^1. — Dipped  20  seconds  in  an  arsenical  dip.  In- 
fested with  seed  ticks  two  days  after  dipping  (August  3). 

August  16  found  a  very  young  nymph  on  calf  941. 

August  20  removed  above  tick  for  examination,  and  determined  that  it  was 
a  specimen  of  Mar  gar  opus  annnlatus.  No  other  ticks  were  found.  No  ticks 
developed  on  calf  956.  This  animal  showed  a  temperature  from  the  sixth  to 
the  twelfth  day.     Calf  941  showed  no  temperature. 

Lot  5  (control).  Calves  Nos.  926  and  938. — Undipped.  August  1  infested  with 
seed  ticks.  Both  of  these  animals  became  heavily  infested  with  ticks  and 
showed  a  rise  in  temperature.  Calf  926  was  down  August  22.  Had  been  down 
since  the  previous  day.  The  animal  was  greatly  emaciated.  It  was  killed. 
Heavily  infested  with  ticks.  There  were  no  lesions  of  Texas  fever.  Smears 
from  liver  and  spleen  contained  no  piroplasma.  On  August  16  both  of  the 
above  animals  were  treated  with  a  subcutaneous  injection  of  150  c.  c.  of  a  1 
per  cent  solution  of  trypan  blue.  Calf  938  was  killed  August  30  for  the  pur- 
pose of  noting  whether  the  stain  from  the  trypan  blue  still  persisted.  On  post- 
mortem both  carcasses  were  found  to  be  extensively  stained.  The  parts  stained 
were  as  follows:  The  skin;  subcutaneous  and  intermuscular  connective  tissue: 
parietal  and  visceral  pleura  and  the  peritoneum;  epicardium,  endocardium,  and 
pericardium;  trachea;  bronchi  and  smaller  air  tubes;  cartilage  of  joints; 
capsule  and  trabecular  of  spleen;  cortex  of  kidneys,  and  the  veins  and  arteries. 
A  pale-bluish  fluid  was  noted  in  some  of  the  mesenteric  lymph  glands. 

The  post-mortems  were  made  6  and  14  days  after  the  trypan-blue  solution 
w;is  injected. 

nrscussioN  of  results. 

It  is  noted  from  the  above  results  that  animals  when  dipped  once 
in  an  arsenical  dip  for  two  minutes  (lot  1)  and  for  20  seconds 
(lot  2)  were  protected  from  infestation  when  exposed  two  and  one- 
half  hours  after  dipping.  This  occurred  when  the  animals  were  not 
exposed  to  rain  and  the  arsenic  on  the  skin  was  not  kept  in  a  more 
or  less  dissolved  state  for  some  time,  as  was  probably  the  case  in 
experiment  No.  1. 

It  is  also  seen  (lots  3  and  4)  that  animals  dipped  for  two  minutes 
and  for  20  seconds  were  protected  from  infestation  when  exposed  two 


THE   PROTECTIVE  ACTION    OF  AESENICAL  DIPS.  25 

full  days  after  dipping.  It  is  believed  that  the  one  young  nymph 
found  13  days  after  infestation  on  calf  941  could  not  have  been  a 
larva  that  attached  itself  at  the  time  of  infestation,  since  its  stage  of 
development  was  considerably  behind  that  of  a  tick  nearly  two  weeks 
old.  It  is  likely  that  this  tick  failed  to  attach  itself,  became  dislodged 
from  one  of  the  calves  after  they  were  placed  in  the  experimental 
paddock,  and  some  days  later  succeeded  in  attaching  itself.  It  is 
possible,  however,  that  this  tick  attached  itself  on  the  day  of  infesta- 
tion. The  writer  obtained  (Bui.  130,  Bureau  of  Animal  Industry) 
in  experiments  conducted  in  1908  a  maximum  period  of  14  days  for 
the  larval  stage,  although  it  is  possible  that  here  also  the  tick  failed 
to  become  attached  at  once.  The  usual  larval  period  is  from  five  to 
nine  days. 

It  is  noted  that  both  of  the  control  animals  became  heavily  in- 
fested with  ticks. 

DEATH    OF    ANIMALS    FBOM    ARSENICAL    POISONING. 

In  the  above  experiment  two  animals  (calves  939  and  955)  died 
from  arsenical  poisoning,  and  it  was  necessary  to  kill  another  (calf 
947)  suffering  from  a  gastric  fistula  due  to  arsenical  poisoning.  A 
number  of  the  other  dipped  animals  suffered  for  a  time  with  anorexia, 
and  some  had  temperatures  that  were  puzzling  and  could  not  with 
certainty  be  attributed  to  Texas  fever.  It  is  possible  that  the}7  also 
suffered  from  arsenical  poisoning.  One  of  the  undipped  (control) 
animals  became  sick,  and  it  was  necessary  to  kill  it.  The  cause  of  its 
sickness  was  not  clear,  but  was  very  probably  Texas  fever.  Although 
it  showed  a  temperature,  there  were  no  lesions  of  Texas  fever  on  post- 
mortem, and  the  piroplasma  could  not  be  demonstrated  on  micro- 
scopic examination.  However,  six  days  previously  it  had  been  in- 
jected with  a  solution  of  trypan  blue.  This  treatment  may  have 
eliminated  the  organism,  which,  if  present  at  all,  was  probably 
present  in  small  numbers,  as  the  animal  was  a  calf. 

The  death  of  three  animals  from  arsenical  poisoning  and  the 
sickness  of  a  number  of  others,  due  possibly  to  the  same  cause,  was 
puzzling  to  the  writer  for  a  time,  especially  in  view  of  the  fact  that 
this  bureau  had  conducted  experimental  dippings  in  arsenic  for  a 
number  of  years  at  the  experiment  station  without  a  single  loss. 
The  analysis  of  the  dip  used  showed  an  arsenic  content  of  0.1652 
per  cent.  This  was  much  too  low  for  the  quantity  of  arsenic  used. 
The  percentage  of  arsenic  should  have  been  0.1925.  It  is  evident 
that  all  of  the  arsenic  was  not  dissolved  when  the  dip  was  made. 
The  most  probable  explanation  of  the  poisoning  is  that  there  was 
undissolved  arsenic  in  the  dip,  and  the  animals  while  being  dipped 
swallowed  enough  to  cause  poisoning.  Support  is  lent  to  this  view 
by  the  fact  that  much  difficulty  was  experienced  in  dissolving  the 


26  ACTION   OF   AESENICAL  DIPS  AGAINST   CATTLE    TICKS. 

arsenic,  because  the  water  was  not  kept  boiling.  After  all  the 
arsenic  had  apparently  gone  into  solution  and  the  strong  solution 
was  added  to  the  water  in  the  vat,  clumps  of  white  particles  were 
seen  floating  in  the  water.  The  writer  at  the  time  assumed  these  to 
be  masses  of  calcium  carbonate  thrown  down  by  the  sodium  carbon- 
ate. It  was  shown  that  this  could  not  have  been  the  case,  however, 
by  observations  made  when  the  batch  of  dip  was  prepared  for  the 
next  experiment  (Xo.  3).  Water  from  the  same  source  was  used, 
and  no  such  precipitate  was  thrown  down  by  the  sodium  carbonate. 
The  only  conclusion  that  remains,  and  this  is  supported  by  the 
analysis  referred  to  above,  is  that  the  particles  observed  were  undis- 
solved arsenic.  If  the  conclusions  here  drawn  with  regard  to  the 
cause  of  the  poisoning  are  correct,  the  extreme  danger  of  having 
undissolved  arsenic  in  a  dip  is  indicated,  and  it  is  possible  that  an 
explanation  of  losses  in  certain  instances  has  been  furnished. 

STAINING    OF    TISSUES    OF    ANIMALS    TREATED    WITH    TRYPAN    BLUE. 

The  extensive  and  intense  staining  of  the  tissues  of  animals  treated 
with  subcutaneous  injections  of  a  1  per  cent  .solution  of  trypan  blue 
has  been  previously  noted  in  the  post-mortems  of  animals  Xos.  926 
and  938.  The  post-mortems  were  made  6  and  14  days  after  the 
treatment.  It  would  be  of  some  practical  interest  to  determine  how 
long  the  staining  will  persist  in  treated  animals,  since  it  appears  that 
it  might  interfere  with  the  use  of  animals  for  beef  purposes  for  a 
considerable  period. 

EXPERIMENT   XO.    3. CATTLE  EXPOSED   TO   INFESTATION    FIVE  DAYS  AFTER 

DIPPING. 

Following  experiment  Xo.  2  another  was  undertaken  to  determine 
whether  arsenic  will  protect  animals  from  infestation  five  days  after 
dipping. 

The  dip  used  in  experiment  Xo.  3  was  made  up  in  the  proportions 
of  8  pounds  of  arsenic  trioxid  and  24  pounds  of  sodium  carbonate  to 
500  gallons  of  water.  Xo  pine  tar  was  used.  The  dip  was  made 
August  29,  and  an  analysis  showed  it  to  contain  0.18G9  per  cent  of 
arsenic  trioxid.    The  results  of  the  experiment  were  as  follows: 

Lot  1.  cattle  Xos.  830  and  SCO.— Dipped  August  2D.  20  seconds.  September 
4  (five  days  later)  infested  cattle  with  progeny  of  ticks  collected  August  S. 
1912,  ;ii  Fori  Worth,  Tex.  Roth  animals  became  grossly  infested  with  ticks 
and  contracted  Texas  fever.  On  September  20  animal  830  died.  Post-mortem 
showed  typical  lesions  of  Texas  fever. 

Lot  8  (control).  Cattle  Nos.  855  and  858. — Undipped.  September  4  infested 
with  progeny  of  ticks  collected  August  S  at  Fort  Worth.  Tex.  Both  animals 
became  grossly  infested  with  ticks  and  contracted  Texas  fever. 


HOW  ANIMALS  ARE   PROTECTED  AGAINST   TICKS.  27 

DISCUSSION    OF    RESULTS. 

It  is  shown  by  the  above  experiment  that  animals  clipped  in  an 
arsenical  dip  containing  0.1869  per  cent  of  arsenic  trioxid  are  not 
protected  from  infestation  when  exposed  five  days  after  dipping. 
It  also  appears  that  the  degree  of  infestation  was  not  influenced  in 
any  way  by  the  dipping  in  arsenic. 

THE    METHOD   BY  WHICH   ANIMALS   ARE   PROTECTED  AGAINST   TICK 

INFESTATION. 

There  are  two  ways  in  which  it  is  conceivable  that  arsenic  protects 
against  infestation :  that  is.  by  rendering  the  skin  unpleasant  to  the 
tick,  and  by  poisoning  the  tick  after  it  attaches.  Support  is  lent  to 
the  latter  view  by  the  fact  that  dead  larvae  were  found  attached  to 
the  skin  of  calf  955  at  the  time  of  its  death  three  days  after  it  was 
infested.  It  was  not  practicable  to  multiply  observations  similar  to 
the  above  because  of  the  great  length  of  time  consumed  in  locating 
the  seed  ticks  on  the  animals. 

The  results  of  the  experiments,  however,  have  proved  conclusively 
that  the  protection  is  due  to  the  larva?  being  killed  and  not  to  their 
being  repelled.  The  animals  when  seed  ticks  were  applied  to  them 
were  placed  in  a  special  pen  set  aside  for  that  purpose,  and  several 
hours  later,  after  the  ticks  had  had  time  to  attach  themselves,  were 
placed  in  the  tick-free  pens  they  were  to  occupy  during  the  experiment. 
If  arsenic  possessed  simply  a  repellent  action  effective  for  two  days, 
complete  protection  would  not  have  resulted  as  occurred  in  the  ex- 
periments, since  the  larva?  would  either  have  wandered  about  over 
the  hair  of  the  animals  or  have  become  dislodged,  only  to  become 
attached  later  when  the  repellent  action  of  the  dip  had  ceased  to  be 
effective.  It  is  therefore  seen  that  if  we  were  dealing  with  a  re- 
pellent action  instead  of  a  toxic  action  at  least  a  certain  degree  of 
infestation  must  have  resulted  in  the  case  of  all  of  the  dipped  ani- 
mals, unless,  of  course,  all  the  seed  ticks  left  the  animals  between 
the  time  the  ticks  were  applied  and  the  animals  were  placed  in  their 
permanent  pens,  a  possibility  that  is  too  remote  to  be  worthy  of 
consideration. 


ADDITIONAL  COPIES  of  this  publication 
-£*-  may  be  procured  from  the  Superextexd- 
Ent  of  Documents,  Government  Printing 
Office,  Washington,  P.  C,  at  5  cents  per  copy 


i 


N 


§ 


I 


UNIVERSITY  OF  FLORIDA 


3  1262  08928  6826 


